Container closure and method of closing containers



' @559, 1946. F. GILBERT, JR 2,43 CONTAINER CLOSURE AND METHOD OF CLOSING CONTAINERS u w ,INVENTOR FRANK GILBERT, JR.

- ATTORNEY-5 .en'dvclosures. It isan object end closures employed heretofore. .ticular' advantage of my invention that the pa- :perv elements of my, reinforced closure may be A i 2,-4os,s5'5,-"" Y 'CONTAINERCLOSUREAND METHono CLQSINGCONTAINERS Frank t. J Olmsted Falls, Ohio Appucaitn Julylo, 1942, Serial No. 450,378 I This v n eip ia ns i ro me is container closures'and a method Of CIOS iHgCOH- tainers. 'More particularly, this inventionrelates to stiff, water and jmoistureproof paper closures for cans, jars/bottles, andthe like,.,as. wellfas for, rigid; and s'emi-rigid paper containers. @This application is .a .continuationein-part of my. 00,-. pending applicatiom SerialiNp. 441,649, filed May 4,1942. f, I

Paper container closuresorv en'dfmembers have long been employed for tubular'paper containers. Paper containers for dry, light-weight products, such as, forexample, cereals or like produtcs not critically affected by moisture, usually are comprised of a wound tube of paper stock closed with adhesively secured. paper caps. Such paper caps are stamped or formed from a sheet of lightly calendered and sizedfpaper stock, usually while the stock is damp, so that the caps are provided with an integralflange. Although such caps are inexpensive, the. porosityof the stock I made of standardc cia1 I converting machinery for forming the 636125- and disks is notr'equiredf Because of the strength andfrigidityof. my improved ;end closures, they may be employed as the end ,cl r s lo l g giameme aper containers, such as one, twoj and five gallon buckets and pails, for example. j," It is. another object ofmy invention.t o..,pro-, vide a paper closure which is I substantially m'oisa 'ture and vaporproof andprovides a substantially permanent seal for cans, jars,'bottles, and the like, as well as for paper containers. Itisla'n advantageof my invention that it may befsub-i stituted for, the relatively expensivetin' covers and closures heretofore employed -as'c osures for jars of many foodstuff and other products. 1 An: other advantage of my invention is that no gas.-

from which the caps are made generally renders the caps unsuitablefor packages of wet or liquid products. When wet orliquid products, such as,-for example, ice cream, pickles, and th like, are packaged in tubular paperfcontainers, such containers are usually wound tubes'of heavily calendered and sized paper stock spun in at one end to provide a seat for a tightly fitting paper closure disk; the closure for the other end of such tubes is usually a slip cover comprising a short tube spun in to provide a seat for a second tightly fitting paper disk. Such tubular containers for wet or liquid products are often coated or waxed to render the containers substantially particularly when .the',cross-sectional area of the tubular container is relatively large. In such instances, standard paper closures possess neither theJStrength nor rigidity afforded by the metal ofthis invention to provide a reinforced paper container closure which apketing. material,' such like,isrequired.

A still furtheradvantage of my invention is that, while heavily calendered and, sized,. D.aper stockmay be'employed in some instances, in most instances cheap porous stock is preferred for my containerclosures. V Other objects and advantages of my invention will be apparent from the following specification, claims,and'drawings' in which: w

.Fig. 1 is an exploded, sectional viewillustrating one method of making my closures.v j

Fig. 2 is a sectional view of a tubular paper container closed at one end with a reinforced closure made according to my invention. 7

Fig. 3 is a sectional View ofa'modified reinforced closure made according to my invention. Fig. 4 is a sectional view of a wide mouth glass container closed with a closure made according tomyinvention. V Inthe-drawings, in which like reference characters refer to like parts or elements, the thicknesses ofthe elements are distorted for clarity of illustration. In Fig. 1, l0 represents a stand' ard stampedcap of relatively porous paper stock provided with a flange II integral with the bottom l2. A quantity of a normally substantially solid impregnating and filling agent 20 is poured in the cap ill in a liquid and impregnating conas rubber, cork, or the dition. While the impregnating agent/2U is' in a liquid and impregnating condition, a porous paper reinforcingsheet 3B is immersed in the impregnating agent 20. The reinforcing sheet 30 is preferably a disk or sheet of porous paper-board, such as the'corrugated paper-board comprised of a corrugated-sheet 3| and cover sheets 32 and 33, as shown inFig. 1. a 7 Due to the porous and capillary nature of the aps and, so

of the impregnating agent upon solidification,

slight voids 2| in the impregnating agent may be found under the corrugations in the sheet 3| and the cover sheet 33. Due to the film strength of theimpregnating agent, a film 22 of impregnating agent will usually separate the bottom I2 from the cover sheet 32. By employ-E ing a suflicient quantity of impregnating agent 20, a film 23 of impregnating agent will cover the cover sheet 33.

By allowing the impregnating agent 20 to solidify, the cap l0, impregating agent 20 and. re-

inforcing sheet 30 become a strong and especially rigid unit in which the paper elements are thor-r oughly united by the solidified impregnating agent.- For some reason, the impregnated fibrous paper elements appear to have greater strength and rigidity than the sum of the strength and rigidity of the paper elements and an equal thickness of the impregnating agent. stricting myself to one theory, I believe this greatly increased strength is due to the relatively high film or surface strength of the impregnating agent. By impregnating the agent in the fibrous elements and providing a plurality of films of the agent, the surface area of the solidified impregnated agent is many times greater than the surface area of a homogeneous quantity of impregating agent of the same thickness. The voids 2|, unless excessive, do not appear to appreciably decrease the strength and rigidity of the closure, since, as pointed out above, the strength of the closure appears to be primarily attributable to the impregnated paper elements.

As is apparent from the foregoing, the impregnating agent should be normally solid but should be obtainable in a liquid and impregnating condition. It is also preferable that the impregnating agent be impermeable to the liquids and gases either which should be retained in the packaged contents or from which the contents should be protected. Such liquids and gases are commonly water and water vapor. The impregnating agent is preferably meltable in order that heat alone will render the impregnating agent liquid, although soluble impregnating agents or agents which are polymerizable or which are resinous condensation products may be employed. I have found that an inexpensive'impregnating agent which is normally solid, water and moisture vapor proof, and meltable is a solution or mixture of paraffin wax and pine rosin. Such a mixture is solid but less brittle than either of its-constituents. Where the paraffin-pine rosin impregnating agent is not sufiiciently inert to the products to be packaged, a wide range of other, but usually more expensive impregnating agents are available to those skilled in the art. For example, a particular inert impregnating agent which will greatly increase the strength, rigidity, impermeability, and hardness of the closure is alcohol-modified urea-formaldehyde resin condensed and polymerized (thermo-set) in the fibers of the paper elements.

When a reinforced cap type of closure, such as shown in Figs. 1 and 2, is employed, the closure may be secured to a container with suitable adhesives. When a meltable impregnating agent, such as my paraffin-pine rosin mixture, is em- Without reployed, a convenient manner ofsecuring the closure to a container is to seat the open end of the container, having outside diamensions equal to the inside dimensions of the flange against the reinforcing sheet 30 as the impregnating agent is allowed to cool. In such instances, the impregnating agent will creep between the inner wall of the flange and the outer wall of the container so that, upon solidification of the impregnating agent, the closure will be securely sealed to the container. If the container is a spirally wound paper tube 40, as shown in Fig. 2, the impregnating agent will also impregnate the closed end of the container to a certain extent, depending upon the porosity of the paper in the container All. I

Fig. 3 shows adisk type of paper closure made according to my invention, in which a spira1 wound paper container I40 is closed in the conventional manner by a disk I 2 seated on a spunin flange The closed container I40 thus affords a shell, similar to the cap for receiving a quantity of the liquid impregnating agent 20. A reinforcing sheet |30 of porous paper stock is then immersed in the liquid impregnating agent. As the impregnating agent solidifies, it thoroughly impregnates the reinforcing sheet I30, the inner surface of the disk H2, and the inner surface of the container M0, thus providing a strong, rigid, and sealed closure.

My reinforcing sheet need not be a sheet of corrugated paper-board, as shown in Figsfl to 3, but may be a single ply of porous'paper stock, such as paper-board, straw-board, chip-board, or the like. Further, my closures are not limited to use on paper containers, An example of a single ply reinforcing sheeet and an example of my closure applied to a container having nonporous walls is shown in Fig. 4. A paper cap 2H1 having a flange 2| integral with the bottom 2|2 is filled with a quantity of liquid impregnating agent 29. A single ply reinforcing sheet 230, in this instance previously secured to the mouth of a glass 240, filled, for example, with jelly, is then immersed in the impregnating agent. In order that the impregnating agent 2|] may also serve as a seal, it should also wet the. surface of the non-porous container 240. Thus, a sufficient quantity of the impregnating agent is employed so that when the mouth of the container closed by the reinforcing sheet is immersed in the impregnating agent, the impregnating agent will be forced up between the flange 2H and the walls of the container. Due to the wetting action of the impregnating agent, the agent will tend to creep up the outer walls of the container 240. When the impregnating agent has solidified, a thoroughly sealed rigid closure for the glass 240 will be provided.

In the embodiments disclosed, the reinforcing sheets have been impregnated by immersing the porous reinforcing sheets in a quantity of liquid impregnating agent in the standard paper. closure. This method is usually preferred because of the simplicity of operation and because no special closure forming machinery is required. However, the standard closure and reinforcing sheet may be impregnated separately and then united. by placing the impregnated reinforcing sheet in the impregnated closure. The application of heat and pressure, in the case of meltable impregnating agents, or a solvent andpressure, in the case of soluble impregnating agents, will weld the impregnated closure and reinforcing sheet together. Another satisfactory method of pregnate the exposed surface of the reinforcing sheet and, by flowing through the holes in the reinforcing sheet, will seep between and impregnate the adjacent surfaces of the reinforcing sheet and the cap. The few small holes in the reinforcing sheet do not materially affect the strength of the reinforced closure when the impregnating agent has solidified.

Meltable impregnating agents containing substantially no volatile solvents are generally preferred. Solvent loss, the minute porosity caused by evaporation of the solvent, and escape. into and possible contamination of the contents of the closed containers are thus avoided. When meltable impregnating agents are employed, care must be taken to secure thorough impregnation of the paper elements of the closure by preventing an over-rapid cooling of the impregnating agent. Where my closure is used toseal a con- ,tainer filled with heated contents at or near the melting point of the impregnating agent, such over-rapid cooling is usually prevented. Otherwise, it is often advisable to apply heat by suitable hot plates or ovens until the impregnating agent thoroughly impregnates the closure.

Although the paper containers in the embodiment disclosed have wall portions which are made of spirally wound paper tubing having a circular cross-section, it is not to be understood that my invention is to be limited to paper containers having such wall construction. For example, my invention may be employed to reinforce the closures of the so-called collapsible cartons in which the walls are formed from a blank of paper stock formed into a. tube having a rectangular cross-section and the end closures are normally formed by interfolded flaps integral with the tubular walls. Therefore, it is to be understood that the term tubular paper containers as employed in the claims may apply to wound containers, either spiral or convolute, or folded containers, of either the collapsible or setup type, and that the term tubular applies to tubes having a polygonal cross-section as well as a circular cross-section.

From the foregoing, it is apparent that the embodiment disclosed may have to be varied by those skilled in the art to meet the needs and requirements of specific types of containers and products to be packaged in such containers. Further, normally solid impregnating agents which may be satisfactory for one type of prod.-

uct or container may not be satisfactory for others. It is apparent, therefore, that my invention is not limited to the specific embodiments disclosed, but may be varied by those skilled in the art within the scope of the appended claims.

What "is claimed is: 1. As an article of manufacture, a stamped 7 paper cap comprised of an integral bottom portion and a flange portion, a reinforcing sheet of corrugated paper comprised of a central corrugated sheet and cover sheets, said reinforcing sheet being located within said cap and covering the inner surface of said bottom portion, and a solid impregnating agent substantially completely filling the voids of said reinforcing sheet and impregnating the inner surface of said cap to unite said cap and reinforcing sheet into a rigid container closure.

2. The method of making a, rigid paper container closure comprising the steps of placing a quantity of normally solid molten impregnating agent in a paper container closure cap, immersing a paper reinforcing sheet in said molten impregnating agent, allowing said impregnating agent to-impregnate adjacent surface portions of said cap and sheet, and then allowing said impregnating agent to become solid to unite said impregnated cap and sheet.

3. The method of sealing and reinforcing the bottoms of containers comprising the steps of placing in an open-ended paper container having a porous paper bottom a quantity of normally 4 solid impregnating agent while said agent is in a liquid state, immersing a sheet of porous paper stock in said impregnating agent to cover the bottom portion of said container, allowing said impregnatin agent to impregnate adjacent por tions of said reinforcing sheet and said container, and then allowing said impregnating agent to solidify.

4. The method of closing containers comprising the steps of placing in a paper cap a quantity of normally solid impregnating agent while in a liquid state, covering the mouth of a container with a paper reinforcing sheet, inverting said container and forcing the paper sheet covering the mouth of said container below the surface of the liquid impregnating agent in the cap, said cap, container mouth, and quantity of impregnating agent being so proportioned that a portion of the impregnating agent will be extruded between the cap and the walls of the container adjacent the mouth of the container, allowing said impregnating agent to impregnate adjacent surface portions of said cap and sheet, and then 3.1-

FRANK GILBERT, JR. 

